Conduct-disordered behavior in preschool-age children represents the single most important behavioral risk factor for later antisocial behavior and can be reliably identified in children as young as 3 years. Early intervention may be critical. Without treatment, conduct-disordered behavior is highly persistent and worsens with time. Evidence indicates that the short-term effects of interventions at preschool age are highly effective, may be more effective than treatments when children are older, and may prevent many of the associated academic and peer difficulties that require multiple interventions only a few years later. Evidence of the long-term effects of treatment (beyond 1 year), however, are limited. The few studies that exist suggest that beyond the first follow-up year, as many as 50 percent of treated children may return to pretreatment levels. Lack of information about the course of child and family functioning after treatment hinders our understanding of factors associated with treatment failure, and studies of psychosocial maintenance treatments for children are almost nonexistent. This project will test the continuing care model of maintenance treatment that assumes that conduct disorder is a chronic condition requiring monitoring and booster treatment at times of incipient relapse during childhood. Participants will be 100 families of children ages 3 to 6 with Oppositional Defiant Disorder referred to one of two clinics for treatment. Families will be randomly assigned to the standard treatment group (parent-child interaction therapy; PCIT) or to the maintenance treatment group (standard treatment followed by a two-year period of monitoring and treatment-as- needed). We predict significant differences at 2-year follow-up favoring the maintenance treatment group in child and parent functioning assessed by multiple method/multiple informant measures across settings. We expect responsiveness to treatment in both groups to be influenced most strongly by parent psychological variables. Predictors of outcome will be examined separately for the African American subgroup to inform the development of a culture specific treatment protocol.